TOPLESS co-repressor interactions and their evolutionary conservation in plants

Abstract

Large-scale protein-protein interaction studies recently demonstrated that the Arabidopsis TPL/TPR family of transcriptional co-repressors is involved in a broad range of developmental processes. TPL/TPRs predominantly interact with transcription factors that contain repression domain (RD) sequences. Interestingly, RDs reported in the literature are quite diverse in sequence, yet TPL/TPRs interact with proteins containing all of the known motifs. These data lead us to conclude that the TPL/TPRs act as general repressors of gene transcription in plants. To investigate this further, we examined interactions between TPL/TPR proteins encoded by the moss Physcomitrella patens genome and components of the auxin signaling pathway. As in Arabidopsis, moss TPL proteins interact with AUX/IAA and ARF proteins, suggesting that they act in both forms of ARF-mediated transcriptional repression. These data suggest that the involvement of TPL in auxin signaling has been conserved across evolution, since mosses and angiosperms diverged approximately 450 million years ago.

Ubiquitin-Mediated Control of Plant Hormone Signaling

“…However, there are also likely to be some differences. In fact, all of the UPS components and protein-protein interactions involved in auxin signaling, including the F-box coreceptors and TPL-Aux/IAA-ARF interactions, appear to be conserved in the moss Physcomitrella patens (Prigge et al, 2010;Causier et al, 2012). Over 30 plant genomes are now available at Phytozome (Goodstein et al, 2012), providing ample opportunities for in silico identification of UPS components for further study.…”

AUXOLOGY: When auxin meets plant evo-devo

“…Similarly, loss of functional domain I motif (LxLxL) that confers transcriptional repressor function of Aux/ IAAs occurred independently several times during evolution of land plants ). However, the moss Aux/IAA proteins that contain the non-canonical motif LxLxPP may still interact with TPL (Causier et al, 2012), challenging the idea that loss of domain I motif LxLxL could affect Aux/IAA function.…”

Comparative transcriptional analysis provides new insights into the molecular basis of adventitious rooting recalcitrance in Eucalyptus

“…TOPLESS (TPL) is a member of the Groucho (Gro)/Tup1 family of co-repressors and has been shown to be involved in a broad range of signaling pathways in plants [17]. These proteins interact with transcription factors to repress gene expression in different processes by the recruitment of histone deacetylases and modification of chromatin state to inactive [57].…”

“…This complex acts to repress auxin response genes and TPL is required for IAA12/BDL repressive activity [16]. Together with the TOPLESS-RELATED PROTEINS (TPRs), TPL participates in repression of auxin-related genes [17], likely affecting AR. Some ARFs are also involved in rooting.…”